People often take their drinks with them when commuting or otherwise driving or walking place to place. Coffee drinkers, for example, have had to rely on a variety of coffee travel cups and disposable "to go" cups. The common generic plastic travel cups with attachable lids are convenient to use, but have several disadvantages. For example, plastic cups and lids are easily scratched, retain grime and dirt, develop permanent stain markings, and are difficult to clean due to being relatively deeper and narrower than average size cups. The attachable lids are not adaptable to a wide variety of cups and fit only one diameter.
The disposable Styrofoam and paper cups that have dominated the "coffee to go" market sold at convenience stores and fast-food restaurants are used once and discarded, creating waste and undue expense. The usual lids associated with Styrofoam and paper cups are commonly made of thin, molded plastic and offer no insulating protection from the hot beverages. This situation can result in difficulty drinking and handling that are especially hazardous in a moving vehicle.
Numerous drinking lids have been created to avoid spills. A patent to Magnus (U.S. Pat. No. 1,254,251) discloses a drinking lid for use with tapered cups or glasses. Specifically, the patent discloses a drinking lid constructed of a concave rubber disk, an enlarged bead formed around the rim of the disk, and notches formed in the outer projecting wall of the bead. However, the Magnus lid cannot adapt to seal the tops of mugs or glasses of differing diameters. The large bead around the Magnus lid causes it to be only minimally flexible. Thus, the acceptable range of container diameters is quite narrow if the lid is to fit within the top of the container. The lid must also be used with containers that taper toward the bottom of the container. Coffee mugs typically do not taper, however. The Magnus lid may also be difficult to remove from the drinking container. Also, the rubber material of which the Magnus lid is constructed may degrade over time and loose its resiliency. This could especially be a problem if the lid is subjected to heat or sunlight.
Other lids have been created that may be secured to the rim of a cup or glass. However, these lids can fit only one container diameter and may even require a specific rim thickness to properly seal.
Therefore, a one-piece drinking closure that is adaptable to a wide variety of drinking containers, such as ceramic coffee mugs, is desirable to allow the use of ceramic mugs and various other containers as travel cups.